Given that he was in Australia under refugee status, and given the letters and association with assaults, why wasn't his refugee status revoked once he started giving off jihadi vibes years ago?

This is not a criticism of the Aussies per se, Lord knows we in the USA drop the ball as badly or worse on these things, but it would seem, moving forward, to be a good practice to give this sort of thing a bit better scrutiny, wherever it may come up.